Conferencing systems allow users to conduct multimedia conferences from multiple locations. A conference may allow users located in one or more cities to meet as if all the users were in the same physical location. The conference may be a video/audio conference or any form of multimedia conference.
Conferencing systems may offer a number of features for the benefit of users. For example, muting may be used to allow some of the participants to engage in other activities during the conference. In another example, record and rewind features may allow the conference to be recorded and may allow a recorded conference to be replayed for conference participants and others.
Each of the users of a conference may produce an audio stream. The audio stream may include the audible comments of the user. A sidebar feature may be used that allows two or more parties within an ongoing conference to create a separate media path that their audio streams are only available to themselves, but not the rest of the conference members. In this situation, the audio stream of the ongoing conference may be still audible to the sidebar members. The sidebar feature may be used for inter-party comments, explanations, and secrets during the conference so as not to disturb the rest of the conference parties.
Various protocols may be used to allow a conference to be set-up and conducted. For example, the Session Description Protocol (SDP) may be used to communicate information between servers and users in order to set-up a conference. The SDP specifies the format of messages allowing the set-up of the conference. One example of the SDP is described in RFC 2327 promulgated by the Internet Engineering Task Force (IETF).